5520 wont print black ink

can someone please help me with this issue.. my 5520 wont print black.. it prints color ok and it also prints grey it just wont print black it stopped working after i replaced the cartridge.. i then replaced the black one a second time and it still doesnt work.. i have tried all of the cleaning suggested and have also cleaned the vent but it looked as as picture and it still doesnt print black.. please help i cant afford new printer and i cant afford to buy ink ...help!!!!